Unusual Looking Martian Rock

NONE | 1-9-04 | Orion78

[Orion78]

The original image from NASA is HERE

Location of Rock in Question

Close Up

[AppauledAtAppeasementConservat]

"A number of minerals crystallize in the cubic (isometric) system and some of them form nearly perfect cubes. One of these is iron pyrite (iron sulphide) -- a likely candidate for this situation because it can be easily dislodged from its host rock matrix or chemically degraded. I've found square holes in rocks where pyrite crystals were formerly located. But there are other cubic minerals that could do the same thing." Interesting that you brought this up. I have been looking into some interesting information that is a theoretical possibility for this hole. First off. Olivine is well known to be present on mars. Now olivine disolves easily in water and if indeed this was a lake bed the it could also explain how a an isometric olivine crystal (obviously megacrystic) that could have formed in the mantel and exposed to water could have disolved away completely or enough to have fallen out of the matrix rock. Here's the articles on the presense of olivine: The first link is good reading on locations of olivine from TES images and the second is the explanation of the formation of isometric olivine in the martian mantle.
http://www.psrd.hawaii.edu/Nov03/olivine.html


http://www.nd.edu/~cneal/eg.101/geology2/geology2.html
Specifically go down to the heading called Expansion of the Martian Mantle to see how isometric olivine occurs on mars. It's possible we could be on to something here... Appearance of this rock look similar to basalt? Certainly darker...

[Orion78]

Thank you very much for your input.

After doing a quick google search, I have discovered that evaporation of salty water produces deposits of the mineral Halite. Halite is salt in it's natural form. Halite has an Isometric structure, (crystals usually look like cubes), and is one of the minerals that NASA scientists are looking for in Gusev Crater. Halite would also erode away very easily and leave a hole in its host rock.

Perhaps "Rectangle Hole Rock" is evidence that Gusev Crater is indeed an ancient lake bed.

[Orion78]

Just a quick note before I hit the hay:

Adirondack, (the name NASA has given to one of the first two target rocks), is also the name of a mountain range in New York that is composed of mostly metamorphic rocks.

http://www.earth.rochester.edu/ees201/GoreckiD/goreckid.html

[AppauledAtAppeasementConservat]

There are now three possible targets one named sushi as well. Sushi and Sashimi are in proximity to each other and adirondack lies northwest of the rover (a triangular rock) about 2-3 meters away. Here's more details:

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2004/01/16/MARS.TMP&type=science
Hope this helps...

[Axenolith]

Kinda like a larger one of these eroded out, and in a basaltic or rhyolytic rock?

[Bernard Marx]

Olivine's interesting -- I have a metallic meteorite specimen that displays large included olivine crystals. It's fascinating. So are your links.

Olivine is the same as the gemstone peridot. It's usually associated with volcanics like basalt -- in fact it's the only gemstone found in Hawaii. But I'm only familiar with the type that crystallizes in the orthorhombic system.

At first I was going to discount olivine as a possibility but the information about its ability to crystallize in the isometric system under certain conditions -- something I didn't know -- made me think again. You've done some serious homework here! That, combined with the spectroscopic evidence in the first link, could make an interesting case for olivine. Of course we're not sure the dark area is a hole yet. But it's loads of fun to speculate.

[MissAmericanPie]

This is the first I have heard about the conditions in Maine. What in the world? Has it ever been that cold there before or is this a record breaker? There is no way your average central heat can keep up with that kind of cold.

[Bernard Marx]

Halite has an Isometric structure, (crystals usually look like cubes), and is one of the minerals that NASA scientists are looking for in Gusev Crater.

Yes, salt xls would be an interesting discovery indeed, and that hadn't occurred to me. For fun sometime look at some table salt under magnification, at least 10x. You'll find nice little cubic xls you'd probably never have suspected.

Don't forget that diamonds crystallize in the cubic system too! As long as we're speculating, let's go first class.

[AppauledAtAppeasementConservat]

Breccia maybe. Rhyolite I dunno...rhyolite would probably fracture differently than the rock in question but then again...I don't know more than basic rocks and minerals and really not enough of it to even be considered slighty authoritative on the subject...maybe lesser gravity could play a role in the formation and charactoristics of the rock. It's all supposition for me.

Maybe Bernard could speculate on this...

[Axenolith]

Oh, the one I posted is a phenocryst in a granitic rock. It's just the west side of Sonora Pass.

That's with a Mavica too, I just got a 6.3 Mp Canon Digital Rebel and I am ITCHING to get out in the hills with it and fill stacks of CD ROMs :)

[AppauledAtAppeasementConservat]

Thanks. You got 30+ years on me in this area so I am reaching here but it seems feasible from what I have read about it. Another speculation is that the presence of olivine in quantity most likely would have ruled out gusev as a mission target because it would probably have ruled out lake quantities of water being present very long as well. If water did exist in quantity then it would have likely interacted with the olivine crystals. I think that rock looks like basalt or breccia because of what seems like banding on the front side of it. If only we could reach out and pick it up!!!

How large would you estimate the olivine crystals to be in your meteorite?

[Bernard Marx]

Breccia maybe. Rhyolite I dunno...

If we're talking about the rock with the square hole, large crystals generally occur in igneous or metamorphic rocks that cool very slowly, giving crystals the opportunity to form. The finest gem crystals, for instance, are usually found in very slow-cooling granitic pegmatite dikes. Rhyolite is a fine-grained fast-cooling igneous rock with very small crystals, and breccia can be any rock that's been fractured and resealed after forming.

Basically, granite pegmatites form when plutonian magma travels upward through fractures in the mantle but isn't able to reach the surface. It forms dikes and sills that are far enough away from the source magma to allow cooling over time. These rocks are exposed on the surface through erosion -- or maybe an explosive event like a meteorite impact.

Crystallization also occurs in hydrothermal (hot water) deposits and slow-cooling metamorphic rocks (usually they're associated). The finest gem rubies, for instance, are found in a white marble (metamorphosed limestone). These are called "contact minerals" that form in even sedimentary rocks that are in contact with hot igneous rocks and magmatic solutions.

[Bernard Marx]

How large would you estimate the olivine crystals to be in your meteorite?

They're pretty small, maybe 3 to 8 millimeters in diameter. They're not well crystallized either, being grouped together in a nodular mass.

Olivine is often associated with basalt "bombs" -- volcanic ejecta that are hosts to masses of olivine. I think the occurrence in meteorites is similar to that type of formation, but who really knows? Some of the olivine-containing meteorities are thought to come from Mars but I'm sure others are from the asteroid belt, remnants of the guts of some ancient planetary body that got smashed to bits.

I'll pick up the discussion when I can over the next day or two. I have to hit the sack for now. Thanks all for an interesting discussion.

[Positive]

Isn't it "nuh nuh nuh, nuh nuh nuh...nuh nuh nuh, hey hey now, nuh nuh nuh"?.

[AppauledAtAppeasementConservat]

Sonona pass? Yeah you could fill tons of cd's with images from CA terrain!

I was at Ft. Irwin outside of Barstow for a few weeks and all over the hill sides out there as an RTO for my fist platoon back in '94. It was a like a moon scape to me. I was on the Matterhorn pretty much the whole time and the granites there were gorgeous. I remember these redish mudstone rocks all over the place that looked like they had feldspar crystals in them. That and a kangaroo rat for a pet each night as I recall always eating my MRE left overs. I'll have to dig out my photo's and see if I still have that picture of him and those rocks.

Those kangaroo rats were something else...every time it started to get dark right after sunset those darn things would come out by the millions and proceed to jump on and over my sleeping bag for half the night! And I do mean millions of them.

Awesome country out there. I just wish I had more time to explore it rather than playing OPFOR against the 1st cav...of course that was fun too...

[AppauledAtAppeasementConservat]

"Olivine is often associated with basalt "bombs" -- volcanic ejecta that are hosts to masses of olivine. I think the occurrence in meteorites is similar to that type of formation, but who really knows? Some of the olivine-containing meteorities are thought to come from Mars but I'm sure others are from the asteroid belt, remnants of the guts of some ancient planetary body that got smashed to bits."

Don't know about asteroids but I think I read somewhere a while back that there was/is olivine on the moon as well. I'll see if I can't find anything out about it and post it here as well.

Great discussion and info! Gotta hit the sack too.

[AppauledAtAppeasementConservat]

"If we're talking about the rock with the square hole, large crystals generally occur in igneous or metamorphic rocks that cool very slowly, giving crystals the opportunity to form. The finest gem crystals, for instance, are usually found in very slow-cooling granitic pegmatite dikes. Rhyolite is a fine-grained fast-cooling igneous rock with very small crystals, and breccia can be any rock that's been fractured and resealed after forming." Yes definately talking about the martian rock...looks like a Basalt Breccia to me. The reason I say Breccia is because of researching kimberlite and lamproite pipes a year or two ago and some of the breccias I saw (especially in the lamproites) looks similar on one hand with what looks like large dark bandings visible on the front side of the martian rock. I did a quick google search to see if I could find an example of this kind of breccia and amazingly this popped up!



You gotta read the article on the corresponding link as well:

http://epsc.wustl.edu/admin/resources/meteorites/dhofar287.html

As you can imagine your earlier statement about diamonds speculation must have subliminaly triggered the breccia images...

[Axenolith]

I was thinking in terms of Rhyolite in the areas I've been around like Mammoth, which look like they have a lot of larger masses from post explosive eruptiion rewelding.

For good crystals in dikes, I'm going to try to hit the Morgan Pass area again this spring\summer, the peak just northwest of the pass is striped with aplite dikes and in the lower talus debris I picked out some good plates of mica (~2X2 inches) and a little aquamarine in some of the debris. Might be an emerald or two up there!

Just south of the pass is the Pine Creek Tungsten mine, one of, if not the, largest in the world. There's a couple of them up there, if you wanted a really cool resort\TEOTWAWKI site the Strawberry was for sale last I saw. A practically new facility (1980's), subsequently closed when the Chinese began dumping concentrate on the market. It's in scheelite at the metamorphic roof pendant contact.

I've been working with dirt (ahem...soil!) and water for too long!!!

[Axenolith]

This is the east side of that pass looking south. Once you break over eastward you run into a lot more volcanics, and the surrounding peaks often have roof pendants of metamorphics. It's particularly strong a bit north over Ebbetts pass on Highway 4. The low tree covered ridge running down the left of the valley is a glacial morraine.

That view is from the little scenic overlook on 120 just up the hill from the Marine Mountain Warfare Training Center.

And Levitt falls

Up the canyon roughly paralleling the highway there.

Hurry up spring...Hurry up spring...Hurry up spring... :)

BTW, Thanks for helping make this country the kind of place where you can enjoy this scenery without a lot of whacko's and landmines being scattered all over the place!

[Centurion2000]

fascinating